The primary objective of the Multiple Risk Factor Interfention Trial is to determine whether, for a group of men at above average risk of death from coronary heart disease, a special intervention program will result in a significant reduction in mortality from coronary heart disease. To achieve this objective, a screening program will be conducted to identify approximately 12,000 men aged 35-57 who: are in an upper percentile of the distribution of risk for death from coronary heart disease based on risk factors of elevated serum cholesterol, elevated diastolic blood pressure, and cigarette smoking; do not have pre-existing definite clinical coronary heart disease or other specified causes for exclusion; and are willing to commit themselves to a six-year intervention program.